1. Field
Example embodiments relate to large-scale X-ray detectors that may realize seamless images.
2. Description of the Related Art
A digital X-ray detector outputs an X-ray image photograph or an X-ray fluoroscopic image using an X-ray in form of digital signals. An X-ray detector may be a direct type and/or an indirect type. According to the direct type, a photoconductor directly converts an X-ray to electric charges. In the indirect type, a scintillator converts an X-ray to a visible ray and a photoelectric conversion device such as a photodiode converts a converted visible ray to electric charges.
A direct type X-ray detector includes a plurality of pixel electrodes formed under a photoconductor layer and a signal processing unit for processing electric signals output from the pixel electrodes. According to related technologies, because a photoconductor layer is formed on application-specific integrated circuits (ASICs) in order to manufacture a large-scale direct type X-ray detector, an image is not detected in a seam area due to a seam between the ASICs when the ASICs having the photoconductor layer thereon are tiled in a large-scale. Specifically, during the tiling of ASICs, a seam having a size of at least 100 μm may be generated, thus tissues existing within the seam may not be detected.
When a large-scale X-ray detector is fabricated by tiling ASICs and a through hole formation process in the ASIC is performed on a wafer that completed a back end of line (BEOL) process, a hole with a depth of several hundreds of micrometers is formed on the wafer to contact a metal pad, an inner wall of the hole is insulated by an insulation film, and the hole is filled with a conductive metal. To perform the process, expensive equipment that is not generally used for a silicon process is employed. The process is performed at high temperature that may damage the ASIC. Also, it is difficult to form the hole in the ASIC corresponding to the position of an upper electrode.